1. Field of the Invention
The present invention relates to a vertical type heat processing apparatus and a vertical type heat processing method.
2. Background Art
In the manufacture of semiconductor wafers, various processes including oxidation, film forming and the like, are provided to each semiconductor wafer (substrate), and, for example, a vertical type heat processing apparatus (or semiconductor manufacturing apparatus), in which multiple sheets of wafers can be processed in a batch-type manner, has been employed as an apparatus for performing such processes (e.g., see Patent Document 1). The vertical type heat processing apparatus includes a loading area (transfer area) below a vertical type heating furnace having a furnace port at its bottom portion. In the loading area, a boat (or substrate holding tool) is mounted on a cover adapted to open and close the furnace port, via a heat insulating mount. The boat serves to receive and hold, therein, multiple sheets (e.g., 100 to 150 sheets) of wafers each having a large size, for example, a 300 mm diameter. In addition, a lifting mechanism for carrying in and carrying out the boat relative to the heating furnace by raising and lowering the cover, and a loading mechanism for loading or transferring the wafers between the boat and a carrier (or container) containing the plurality of wafers therein are also provided in the loading area.
The boat is made from quartz, which is quite expensive. The wafers are also expensive, thus the production cost will be more increased with further progress of the processing steps. Accordingly, handling of these components or materials must be carried out with greater care.
However, in the batch-type semiconductor manufacturing apparatus described above, the construction of the apparatus poses various restrictions on the conditions for the software and hardware, as such making it difficult to render the apparatus better suited for an earthquake resistant construction or earthquake-proof function, thus being currently insufficient against earthquake related problems. Therefore, when an earthquake occurs and the apparatus experiences a greater shake, fall down of the boat and serious breakdown of the boat and wafers may tend to be caused, leading to drastic damage.
To address these problems, in the vertical type heat processing apparatus described in the Patent Document 1, a structure for connecting and fixing a bottom plate of the substrate holding tool and the heat insulating mount to each other by using a substrate-holding-tool fixing member is employed.
Patent Document 1: TOKKYO No. 3378241, KOHO
In the vertical type heat processing apparatuses, those employing the so-called two-boat system have been known. This vertical type heat processing apparatus employs two boats and includes a boat table adapted for placing the boat thereon so as to perform the loading of the wafers, and a boat carrier mechanism adapted for carrying the boat between the boat table and the heat insulating mount. In such a vertical type heat processing apparatus, while one of the boats is carried into the heating furnace and subjected to a heating process, the other boat placed on the boat table can be used for loading the semiconductor wafers therein.
However, in the vertical type heat processing apparatus employing such a two-boat system, replacing of the two boats on the heat insulating mount should make it difficult to achieve the structure for connecting and fixing the substrate holding tool to the heat insulating mount by using the substrate-holding-tool fixing member. Thus, there is a risk that the boat mounted on the heat insulating mount, the boat placed on the boat table as well as the boat on the boat carrier mechanism may take a fall when experiencing an external force, such as an earthquake or the like. Previously, the applicant has filed “Vertical Type Heat processing apparatus and Vertical Type Heat processing method”, this invention being intended to prevent the fall down of the boat placed on the heat insulating mount and the boat on the boat table.